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Bluetooth: Fix deadlock in l2cap_conn_del()

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A deadlock occurs when PDU containing invalid SMP opcode is received on
Security Manager Channel over LE link and conn->pending_rx_work worker
has not run yet.

When LE link is created l2cap_conn_ready() is called and before
returning it schedules conn->pending_rx_work worker to hdev->workqueue.
Incoming data to SMP fixed channel is handled by l2cap_recv_frame()
which calls smp_sig_channel() to handle the SMP PDU. If
smp_sig_channel() indicates failure l2cap_conn_del() is called to delete
the connection. When deleting the connection, l2cap_conn_del() purges
the pending_rx queue and calls flush_work() to wait for the
pending_rx_work worker to complete.

Since incoming data is handled by a worker running from the same
workqueue as the pending_rx_work is being scheduled on, we will deadlock
on waiting for pending_rx_work to complete.

This patch fixes the deadlock by calling cancel_work_sync() instead of
flush_work().

Signed-off-by: Jukka Taimisto <jtt@codenomicon.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
Cc: stable@vger.kernel.org
This commit is contained in:
Jukka Taimisto 2014-06-12 10:15:13 +00:00 committed by Marcel Holtmann
parent f8680f128b
commit 7ab56c3a6e
1 changed files with 7 additions and 1 deletions
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8
net/bluetooth/l2cap_core.c
View File

@ -1663,7 +1663,13 @@ static void l2cap_conn_del(struct hci_conn *hcon, int err)
kfree_skb(conn->rx_skb);
skb_queue_purge(&conn->pending_rx);
flush_work(&conn->pending_rx_work);
/* We can not call flush_work(&conn->pending_rx_work) here since we
* might block if we are running on a worker from the same workqueue
* pending_rx_work is waiting on.
*/
if (work_pending(&conn->pending_rx_work))
cancel_work_sync(&conn->pending_rx_work);
l2cap_unregister_all_users(conn);